The HTC One S is HTC's mid-tier smartphone, though the device certainly holds its own in the revolving door that is the smartphone market. Both it and the iPhone 4S are available for $199 on contract U.S. So, if you're considering the two, which should you buy?

Display

The One S has a bigger screen than the iPhone 4S - 4.3 inches and 3.5 inches respectively - though the 4S uses the Retina Display at a 960x640 resolution, while the One S has a 960x540 resolution. While the differences seem small, the 4S has 0.8 inches less in screen size and a 326 ppi display. It comes down to whether users want a bigger screen at a lower resolution, or a smaller screen at a higher resolution.

Hardware

Both phones include LED flash eight-megapixel cameras on the back, and a VGA camera on the front, that supports auto focus. Both devices can capture 1080p video.

The 4S is thinner than the One S: 4.5x2.31x0.37 inches versus 5.15x2.56x0.31 inches. The 4S include a weaker battery, however - a 1432mAh Li Ion compared to the One S's 1650mAh Li Ion.

The devices are available with 16GB of internal memory, but don't support external storage, though the 4S is available in 32 and 64GB sizes for $299 and $399 on contract respectively. iPhone 4S is available on AT&T, Sprint and Verizon while the HTC One S is available on T-Mobile.

Software

In terms of the operating system, the 4S runs iOS 5.1 while the One S runs Android 4.0.3 Ice Cream Sandwich, with HTC Sense 4.0 skin. The major difference is whether you want an experience being controlled by Apple (as iOS can't be heavily modified outside of jailbreaking), or the open source Android OS where users can do almost anything provided you have the time and knowledge. Apple could debut iOS 6 this year - possibly as early as WWDC in June - though that's purely speculation. Android updates release frequently.

On the day Apple revealed record sales in the last quarter, HTC revealed its profits dropped by 70 percent. Largely due to the iPhone 4S, sales of which were slowing down in the U.S., HTC said it won't regain 50 percent of revenue from the United States.

"A major challenge we faced last year was the big drop in sales in the U.S. because of competition from the iPhone 4S," HTC CEO Peter Chou said in an analysts' briefing on Tuesday, April 24, this week.

(reported by Jonathan Charles, edited by Dave Clark)